Amsterdam is worth visiting at any times of the year, although it is at its busiest in July and August, when the weather is generally warmer. The weather, though, is never really extreme at any time of year, and outside of the summer months you’ll find that everywhere is cheaper and less crowded. There are also some interesting events going on, i.e. the bulb fields near Amsterdam are bursting with colour from mid-April to mid-May and the cultural season is in full swing between September and May.